Assuming the population variances are unknown and equal, you wish to test whether the Group 1 population mean is equal to the Group 2 population mean. The resulting test statistic is a Student-t with how many degrees of freedom

Step-by-step explanation:

If we had 2 independent samples with population variances unknown and equal and we want to compare the population mean between the both groups, the test statistic will be:

Where

So, the t-student has degrees of freedom

Where and are the means of the groups, and are the size of the samples and and are the sample variances.

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